<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://unpkg.com/vue"></script>
    <script>
        window.onload=function(){

            Vue.component('my-component',{
                template:'<div>A custom compnent!</div>'
            })

            var app4= new Vue({
                el:'#example'
            })

        }

    </script>
</head>
<body>
<div id="example">
    <my-component> !!! </my-component>
</div>
</body>
</html>